SE527163C2 - Grease, oil and wax resistant paper composition as coatings for paper substrates, comprises cellulose-containing substrate having water based mineral coating comprising filler material, binder and calcium carbonate - Google Patents

Abstract

A grease, oil and wax resistant paper composition comprises a cellulose-containing substrate having a surface area and a water based mineral coating comprising a filler material, a binder and a calcium carbonate, essentially free from surfactants. An independent claim is included for a method of imparting grease, oil and wax resistance to a substrate comprising providing a cellulose-containing substrate having a surface area, comprising individual fibers, paper, paperboard, bagstock, ticket stock, blended or unblended kraft or liner board; applying a water based mineral coating as above.

Description

30 527 163 2 is described in TAPPI T 452 "Brightness of Pulp, Paper, and Paperboard (Directional Rejectanee at 457 nm)".

In addition, the selected coating must withstand the stresses that often occur during processing of the coated paper. In particular, the flexibility of the coating is required for forming containers and packages without the coating fl chipping off or breaking. Smoothness is necessary for high quality Greek printing as well as a high degree of bonding at the paper surface, as measured by the wax-pick text, if required. In addition, the coatings must be able to withstand the transfer stresses of heat, sensation and pressure while the material passes through equipment for punching, cutting, printing, gluing, bonding, withstand similar environments as in the process of transfer to corrugated board, have the ability to be glued with hot melt adhesive. or cold glue and excellent results in fi test must be obtained.

U.S. Patent No. 5,674,961 (Fitzgerald) discloses a typical oil, water and solvent resistant paper. More specifically, a paper, board, paperboard or board substrate is impregnated with a hydrocarbon to obtain hardness. In addition, a synthetic substrate is made cured by impregnation with a fluorinated component, as described in U.S. Patent No. 5,330,622 (Honnotat et al.). Incorporation of such hydrocarbons is well known in the industry as a useful and economical way to impart oil, water and solvent durability to paper and other petroleum products.

Recently, however, U.S. The Environmental Protection Agency (EPA), as well as the Canadian Department of Health and Welfare and the German BGVV have realized that such hydrocarbons can have harmful consequences for health. The EPA has reported that certain orkorocarbons (eg peroorooctanesulfonic acid, its derivatives and salts) have reappeared in the system in humans and other animals, leading to concerns about potentially increasing, reproductive and systemic toxicity. EPA has proposed to produce 10 20 25 30 BT? 163 3 the release of and / or emissions of such chemicals should cease in order to limit accumulation in both animal populations and the environment in order to avoid negative consequences therein. The desire to achieve superior grease, oil and wax-resistant white mineral coatings for food and machine packaging has been the focus of sign and demonstration packaging that remains graphically attractive by resisting fl corners from external and internal sources. Economically formulated, this is also a requirement from industry.

It is indisputable that the requirements of the EPA, Canadian Health and Welfare, German BGVV must be met and all domestic and international requirements must be addressed to enable international distribution. The coating should also be able to be used for the production of new pulp at factories all over the world. The presence of wax or waxy coatings is a problem in mass production retur without return fi cardboard or box material.

There is thus a need in the art to provide a coating which provides grease, oil and wax resistance and which is also environmentally acceptable. Essentially, this means that one must develop a coating that is fi- from fl carbon compounds and emissions of other fl viable organic components (V OC), while maintaining a certain possibility of renewed pulp production and the ability to be applied during the production itself of the paper or during an off-line coating procedure.

SUMMARY OF THE INVENTION The present invention relates to a grease, oil and wax resistant coating composition for paper, board, cartons, bag materials, car materials, liners, bleached or unbleached paper, paperboard and other cellulosic materials, comprising (1) a filler. terial; (2) a binder and (3) calcium carbonate. More specifically, the composition of the invention is substantially free of waxes and harmful chemicals such as carbon blacks and surfactants which are known to impede the desired hardness.

The invention further relates to a paper composition comprising a cellulosic substrate and such a coating and to a process for imparting a substrate fat, oil and wax resistance by applying a coating composition according to the invention.

While binders such as latex, PVC, acrylate, maleic acid, proteins, and fillers such as clay, titanium oxide, talc, sodium hexaniethaphosphate and calcium carbonate are commonly used in coatings of this type, the particular exclusion of hydrocarbons is forms the basis for the invention.

In order to achieve the required level of brightness and the hardness of the finished coated product, it has been found that an exclusion of most surfactants is effective. In addition, the use of calcium carbonate in a micrometer size between 0.6 and 7.5 μm has been shown to be effective. This can optionally be accomplished by a mechanical deagglomeration device. Finally, the coating according to the invention constitutes a preparation which enables a high dry matter content (approx. 75%) to a low dry matter content (approx. 30%).

The coating according to the invention is specially formulated for use with a large number of different paper products, such as paper, cardboard, bag material, ticket material or liner, bleached or unbleached kraft paper, in addition to cardboard or other box manufacturing materials. In a first embodiment, the coating is applied to individual sheets before dewatering and forming the paper structure. In a second embodiment, the coating is applied to a previously formed paper structure, such as a large length of paper unrolled from a roll formed by the paper after forming it. Further objects, features and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the drawings, in which like reference numerals refer to the like parts shown in the like drawings.

DETAILED DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a first embodiment used in applying the coating according to the invention.

F ig. 2 is a side view of a second embodiment used to apply the coating according to the invention.

DETAILED ßnsrauvNmc OF THE PREFERRED EMBODIMENTS The coating according to the invention is specially selected to provide a cellulosic substrate resistant to wax, oil and grease. Essentially, the coating comprises a filler material to impart color and other properties, a binder and calcium carbonate, while being essentially fi- in fi- wax, surfactants and fl hydrocarbons.

The substrate or substrate can be any cellulosic product or cellulosic product. While the coating is specially designed and formulated to be used to provide hardness to paper, board, bag material, ticket material, liner, natural or bleached kraft paper or otherwise processed paper products, it is believed that it is within the scope of the present invention to apply the coating to other cellulosic products, such as clothing (either 100% cotton or a cotton blend), wallpaper or laminated wood products. As such, the coating according to the invention can be used in a number of different environments and in different situations to provide hardness properties. The binder is essentially a polymeric binder used to hold the other materials to the substrate. While such binders as latex, PVC, PVA, acrylates, maleic acid , proteins and combinations thereof ñredrages, is any polymeric binder system that adheres to the surface of the substrate or substrate and holds the filler materials together to be filled.

A large number of different filler materials can be used in the coating according to the invention. While talc, clay (alumina / silica), titanium dioxide, sodium hexamethaphosphate and mixtures thereof are preferred materials, any known filler material can be used.

To give the coating grease, wax and oil resistance, calcium carbonate is added to the coating. While it is known to use calcium carbonate in coatings of this type, the calcium carbonate used in the present invention must exhibit certain properties. The calcium carbonate must be substantially free of surfactants. Surfactants present in an amount above 1.5% can cause undesirable properties, such as loss of color and brightness. By essentially excluding chemicals such as stearic acid, sodium polyacrylate and other wetting agents and chemicals that enable the absorption of grease, oil or hot wax in the surface of the calcium carbonate mineral, color and brightness can be maintained.

Finally, the coating is substantially free of hydrocarbons. As discussed above, carbon dioxide material has been found in the system in animals, including humans, which has led to questions regarding its harmlessness. As a result, the coating of the present invention contains little or no carbon compounds at all.

Preferably, carbon monoxide compounds are present in an amount of less than about 0.002% by weight. The calcium carbonate used in the coating must be small in size. It is convenient for calcium carbonate particles to be formed by grinding, especially wet milling, down to a particle size between about 0.6 and about 7. It is important that the level of surfactant is limited during the grinding process.

The invention is described in more detail with reference to the following non-limiting examples. Calcium carbonate coating formulations prepared as described above were prepared as follows: Example A 111.0 g H 2 O 2.0 g Sodium hexametaphosphate 35.0 g Titanium dioxide (rutile, dry) 222.0 g Calcium carbonate (dry, as described above) 40, 0 g Protein (dissolved in H 2 O, 25% dry matter) 120.0 g Latex of styrene-butadiene-gin (SBR) (50% dry matter) Example B 111.0 g H 2 O 2.0 g Naurium hexametaphosphate 00.0 g Titanium dioxide (rutile , dry) 255.0 g Calcium carbonate (dry, as described above) 40.0 g Protein (dissolved in H 2 O, 25% dry matter) 120.0 g SBR latex (50% dry matter) 10 15 20 25 30 527 163 Example C 111.0 g H 2 O 2.0 g Sodium hexametaphosphate 155.0 g Titanium dioxide (rutile, dry) 100.0 g Calcium carbonate (dry, as described above) 40.0 g Protein (dissolved in H 2 O, 25% dry matter) 120.0 g SBR Latex (50% Ton Substance) Sarnmansätmirigen in each of the above-described examples have been specially selected to exhibit different GE brightness spectra as required in all industry. In particular, the coating in Example A gives an inner range of GE brightness, i.e. vs. about 65 to about 78, while Example B has a lower range, i.e. GE brightness between about 50 and about 65, and Example C gives a center tower row, i.e. GE brightness between about 78 and about 90.

Each of the formulations described above provides superior grease, oil and wax resistance, as will be discussed in more detail below.

The coated paper composition according to the invention can preferably be prepared by either of two methods. In the first process, which is described in detail in U.S. Patent No. 5,858,173 (Propst, In), which is hereby incorporated by reference in its entirety, a coating is added to a substrate in the form of individual to Fig. 1, individual beads, which may be new beads, return beads or a mixture thereof, are coated with the coating according to the invention before the burrs are processed in a typical paper machine 10, which comprises a "wet portion" 11, a headbox 12, a wire 13 and a press section 15, a drying section 16, an adhesive press 18, a calender section 20 and a winding roller 22. An egoutteur roller 14 is arranged at a position approximately 2/3 of the way down the wire 13 to smooth the edges and make the web more uniform. Gravity and suction boxes (not shown) are provided under the wire 13 to remove all water from the coating solution. It is at the headbox 12 that the grooves are mixed with the coating according to the invention to form attached grooves. In a second embodiment of the invention, which is described in detail in U.S. Pat. No. 5,393,566, which is hereby incorporated by reference in its entirety, reference is made to a coating after the paper structure is formed. Referring to Fig. 2, a roll 110 comprising an uncoated paper product is mounted on a unrolling stand (not shown) and allowed to rotate freely to feed the paper (hereinafter referred to as "web 114") from the roll 110. through a portion III with freely rotating drive rollers, only two of which are generally illustrated by the reference numeral 112.

It is understood that other numbers and arrangements of rollers 112 in the portion 111 may be used, since the portion 111 does not constitute a feature of the invention itself.

The coating material 115 according to the invention is held in the trough 116. The level of the coating material 115 is regulated in the trough 116 so that a predetermined amount of coating (not shown) is applied to the roller 117. The roller may rotate in the direction of the arrow to transfer a predetermined amount of coating thereon. not) to the finished surface or front of the track 114. The nip between the roller 118 and the roller 117 controls that the predetermined amount of coating is transferred to the web 114 in an amount greater than that desired in the pre-coated paper or sheet material.

The web 114, which has the coating on its front or finished surface, is transferred around the roller 119 so that the coating comes in the vicinity of a directed flow of fluid, preferably a gas, especially air, so that the coating is measured and the desired amount of coating is removed from the web. 114. The directed fl uidum current may be derived from such a device as an AIRKNIFE (John Waldron Corporation, New Brunswick, NJ) or similar device 120 which can direct a high speed current of fl uidum over the surface of the track 114, which exhibits an excess of be laying thereon, to measure and remove unwanted coating. Such devices include rod coaters, blade coaters, exographic presses and gravure rotary presses. The measured and coated web 114 is then fed to any suitable device to cause the coating to solidify, such as a drying unit 121. The drying unit 121 may be provided with continuous conveying means, such as suitable grooves and bars. , which are well known per se, for handling the measured and coated web 114 until the coating solidifies. The drying unit 121 may be reinforced with associated apparatus comprising cold or hot lufl currents, radiant heaters or microwave heaters, suction devices or similar devices to facilitate at least partial solidification of the coating on the web 121 inside the drying unit 121. Preferably the coating helt is completely solidified at the outlet. 121. Guide rollers 122, 123 are used to remove the now solidified coating web 114 from the drying unit 121. The tensioning unit 124 comprises a series of rollers 125, 126, 127, 128 to maintain the tension in the web 114 with solidified coating in preparation for winding the now coated web 114 into roll form 130. The roll form 130 can be further processed on site or shipped to producers for corrugated boxes or folding board.

Other ways of applying the coating according to the invention can be used within the scope of the invention, extensive spraying, curtain coating, etc.

Independent laboratory testing has confirmed that at dry weights of about 6.5 pounds of pavement (2.9 kg) per 1,000 square feet (93 m2), a barrier is created that is completely oil-resistant when applying oleic and oleic oils at temperatures above 160 ° F (71 ° C). The coating did not allow oil to soak through the substrate to its opposite side, even after 24 hours in an oven at 160 ° F (71 ° C). The same procedure was used on the uncoated surface of the substrate and all the above preparations stopped diffusion or suction when the oil reached the coated surface. Coating weights of about 0.5 pounds (0.23 kg) dry matter per 1,000 square feet (93 m2) ) and higher gives measurable fat, oil e and hot wax barrier values compared to the industry standard of 6.0 pounds (2.7 kg) for typical coatings. In particular, a correct flow of coating material and its correct application at coating weights, dry weight, of about 0.5 to about 8.0 pounds per 1,000 square feet of substrate (equivalent to 0.3 to 3.9 kg) was obtained. per 100 m2 of substrate), with correct binding at fi brema. "Wax pick tests" confirmed the binding. Correct folding and bending qualities were achieved on the coated substrate to achieve easy conversion to packaging containers. U.S. Patent No. 5,3 93 566 (discussed above), achieved the same superior driving and application performance as in the paper mill. The same positive results fi occurred in different tests of the coated substrate regarding all types of required performance, where -the most important was superior resistance to hot grease, hot oil and heated wax. Although the invention has been described with reference to preferred forms of teaching, it is easy to see that various changes and / or modifications can be made within the scope of the idea of invention. In any case, the invention shall be limited only within the scope of the following claims.

Claims (32)

10 15 20 25 527 165 12 Patentlaav A grease, oil and wax paper composition, comprising: a cellulosic substrate having a surface area and an aqueous mineral coating which is substantially fi in fi free of surfactants and wax and comprising: a surfactant material; a binder and calcium carbonate, essentially fi- slightly from surfactants. The grease, oil and wax resistant paper composition according to claim 1, wherein the paper composition has a GE brightness value above about 50. The grease, oil and wax resistant paper composition according to claim 1, wherein the paper composition has a GE brightness value below about 90. The grease, oil and wax resistant paper composition according to claim 3, wherein the paper composition has a GE brightness value of from about 50 to about 90. The grease, oil and wax resistant paper composition of claim 4, wherein the paper composition has a GE brightness value of from about 65 to about 78. The grease, oil and wax resistant paper composition of claim 4, wherein the paper composition has a GE brightness value of from about 50 to about 65. The grease, oil and wax curable paper composition according to claim 4, wherein the paper composition has a GE brightness value fi of about 78 to about 90. 10 15 20 25 30 13 The grease, oil and wax resistant paper composition according to claim 1, wherein the substrate is selected from the group consisting of individual sheets, paper, cardboard, bag material, ticket material or liner. The grease, oil and wax resistant paper composition according to claim 1, wherein the coating is substantially fi- in fi- river fl carbon materials and or fluoromomers. The grease, oil and wax curable paper composition according to claim 1, wherein the filler material comprises at least one of clay, sodium hexametaphosphate, TiO 2 and talc. The grease, oil and wax curable paper composition of claim 1, wherein the binder comprises at least one of latex, PVC, PVA, acrylate, maleic acid and protein. The grease, oil and wax paper composition of claim 1, wherein the calcium carbonate component has a particle size between about 0.6 and about 7.5 microns. The grease, oil and wax paper composition of claim 1, wherein the ratio of coating (dry weight in pounds (kg)) to 1,000 square feet (100 m 2) of surface area of the substrate is about 0.6 ( 0.3) to about 8.0 (3.9). The grease, oil and wax paper composition of claim 13, wherein the ratio of coating (dry weight in pounds (kg)) to 1,000 square feet (100 m 2) of surface area of the substrate is about 0.6 (0 , 3) to about 6.0 (2.9). The grease, oil and wax resistant paper composition according to claim 1, wherein the substrate is in the form of a box. The grease, oil and wax curable paper composition of claim 1, wherein the calcium carbonate component is deagglomerated. l0 ~ 15 20 25 U \ 52713 14 A grease, oil and wax hardening paper coating composition, which is substantially free from waxes and surfactants and comprising: a filler material; a binder and calcium carbonate, substantially free of surfactants. The grease, oil and wax resistant paper coating composition according to claim 17, wherein the coating is substantially fi ° in fi than ork carbonated impurities. The grease, oil e and wax curable paper coating composition of claim 17, wherein the filler material comprises at least one of clay, sodium hexametaphosphate, TiO 2 and talc. The grease, oil and wax resistant paper coating composition of claim 17, wherein the binder comprises at least one of latex, PVC, PVA, acrylate, maleic acid and protein. The grease, oil and wax resistant paper coating composition of claim 17, wherein the calcium carbonate component has a particle size between about 0.6 and about 7.5 microns. The grease, oil and wax curable paper coating composition of claim 17, wherein the calcium carbonate component is deagglomerated. A method of imparting a substrate of grease, oil and wax, which comprises: providing a cellulosic substrate having a surface area, which substrate is selected from the group consisting of individual sheets, paper, cardboard, bag material, ticket material, mixed or unmixed kraft paper or liner; Applying an aqueous mineral coating which is substantially free of wax and surfactants and which comprises a filler material; a binder and calcium carbonate, which are essentially free from surfactants. A method of imparting a substrate fat, oil and wax resistance according to claim 23, wherein the substrate is individual och bres and the coating is applied to a mass containing fi bres. A method of imparting a substrate fat, oil and wax resistance according to claim 23, further comprising the step of unrolling the substrate from a roll and wherein the coating is applied after the substrate has been unrolled from the roll. A method of imparting a substrate fat, oil and wax resistance according to claim 23, further comprising grinding the calcium carbonate component, prior to application. The method of providing a substrate with grease, oil and wax resistance according to claim 23, wherein the calcium carbonate component has a particle size between about 0.6 and about 7.5 microns. A method of imparting a substrate fat, oil and wax resistance according to claim 23, further comprising: drying the calcium carbonate component and processing the dried calcium carbonate component in a mechanical de-agglomerator. A method of imparting a substrate fat, oil and wax resistance according to claim 23, wherein the application is carried out in such a way that the ratio between coating (dry weight in 527 163 16 pounds (kg)) and 1,000 square feet (100 m2) surface area of the substrate is about 0.6 (0.3) to about 8.0 (3.9). A process for imparting a substrate fat, oil and wax resistance according to claim 23, wherein the application is carried out in such a way that the ratio of coating (dry weight in pounds (kg)) ooh 1 ooo kvaamfof (100 m2) surface area of subso -otof is oo 0.6 (0.3) 1111 about 6.0 (2.9). A method of imparting a substrate fat, oil and wax resistance according to claim 23, wherein the filler material comprises at least one of clay, sodium hexametaphosphate, TiO 2 and talc. A method of imparting a substrate fat, oil and wax resistance according to claim 23, wherein the binder is at least one of latex, PVC, PVA, acrylate, maleic acid and protein.